JP2013248193A - Golf club shaft - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light-weight golf shaft with excellent strength.SOLUTION: A shaft 6 has a plurality of full length layers s2, s3, and s6-s9. The full length layers have full length bias layers s2 and s3, and full length straight layers s6, s8, and s9. When a layer in which a matrix resin includes a novolac type epoxy resin is defined as a novolac-containing layer, the full length straight layers s6, s8, s9 located outside the full length bias layers s2 and s3 include the novolac-containing layer. In the novolac-containing layer, a content Rn of the novolac type epoxy resin is 3 mass% or larger and 19 mass% or less. If the average specific gravity of the novolac-containing layers constituting the full length straight layers is defined as S1, and the average specific gravity of the full length bias layers and the layer on the inner side of the full length bias layers is defined as S2, the specific gravity S1 is larger than the specific gravity S2.

Description

  The present invention relates to a golf club shaft.

  From the viewpoint of increasing the head speed, a lightweight golf club shaft is required. Japanese Patent Application Laid-Open No. 2000-93658 discloses a lightweight and high-strength golf club shaft.

JP 2000-93658 A

  The weight reduction of the carbon shaft can be achieved by reducing the matrix resin. However, the weight loss of this matrix resin is approaching its limit.

  On the other hand, by increasing the tensile modulus of the fiber and reducing the amount of fiber, the weight can be reduced while maintaining the rigidity. In this case, however, the strength decreases.

  An object of the present invention is to provide a lightweight and high strength golf club shaft.

  The shaft of the present invention is a laminate of fiber reinforced resin layers. This shaft has a plurality of full length layers. The full length layer has a full length bias layer and a full length straight layer. When the layer in which the matrix resin contains a novolac type epoxy resin is a novolac-containing layer, the full-length straight layer positioned outside the full-length bias layer includes the novolac-containing layer. In the novolac-containing layer, the matrix resin contains an epoxy resin component. The content Rn of the novolac type epoxy resin in the epoxy resin component is 3% by mass or more and 19% by mass or less. When the average specific gravity of the novolak-containing layer constituting the full length straight layer is S1, and the average specific gravity of the inner layer of the full length bias layer and the full length bias layer is S2, the specific gravity S1 is higher than the specific gravity S2. large.

  Preferably, the full length straight layer has an outermost full length straight layer located on the outermost side among the full length layers. Preferably, the outermost full length straight layer is the novolac-containing layer.

  Preferably, the N layer located on the outermost side of the full length straight layer is the novolac-containing layer. Preferably, this N is 2 or more.

  Preferably, the N is 3 or more.

  Preferably, the M full length straight layer which is the novolac-containing layer is provided. Preferably, all of these M layers are located on the outermost side of the full length layer.

Preferably, the fiber elastic modulus in the novolac-containing layer located outside the full length bias layer is 8 t / mm ² or more and less than 38 t / mm ² . Preferably, the fiber elastic modulus in the full length bias layer is 38 t / mm ² or more and 70 t / mm ² or less.

Preferably, the fiber elastic modulus of all layers positioned inside the full length bias layer is 38 t / mm ² or more and 70 t / mm ² or less.

  A lightweight and high-strength shaft can be obtained.

FIG. 1 shows a golf club provided with a shaft according to an embodiment of the present invention. FIG. 2 is a development view of the shaft according to the embodiment of FIG. 1. FIG. 3 is a plan view showing a first united sheet according to the shaft of FIG. 2. FIG. 4 is a plan view showing a second united sheet according to the shaft of FIG. FIG. 5 is an enlarged cross-sectional view of the shaft of FIG. FIG. 6 is a development view of the pipe according to the embodiment. FIG. 7 is a plan view showing a united sheet according to the pipe of FIG. 8A, 8B, and 8C are diagrams for explaining the tensile test. FIG. 9 is a diagram for explaining the three-point bending test.

  Hereinafter, the present invention will be described in detail based on preferred embodiments with appropriate reference to the drawings.

  In the present application, the term “layer” and the term “sheet” are used. A “layer” is a designation after being wound, whereas a “sheet” is a designation before being wound. A “layer” is formed by winding a “sheet”. That is, the wound “sheet” forms a “layer”. Moreover, in this application, the same code | symbol is used by a layer and a sheet | seat. For example, the layer formed by the sheet s1 is the layer s1.

  In the present application, “inner side” means the inner side in the shaft radial direction. In this application, “outside” means the outside in the radial direction of the shaft.

  In the present application, the “axial direction” means a shaft axial direction.

  In this application, the angle Af and the absolute angle θa are used with respect to the angle of the fiber with respect to the axial direction. The angle Af is an angle with plus or minus. The absolute angle θa is an absolute value of the angle Af. In other words, the absolute angle θa is an absolute value of an angle formed by the axial direction and the fiber direction. For example, “the absolute angle θa is 10 ° or less” means “the angle Af is −10 degrees or more and +10 degrees or less”.

  FIG. 1 shows a golf club 2 having a golf club shaft 6 according to an embodiment of the present invention. The golf club 2 includes a head 4, a shaft 6, and a grip 8. A head 4 is provided at the tip of the shaft 6. A grip 8 is provided at the rear end of the shaft 6. The head 4 and the grip 8 are not limited. Examples of the head 4 include a wood type golf club head, a hybrid type golf club head, a utility type golf club head, an iron type golf club head, and a putter head.

  The head 4 of this embodiment is a wood type golf club head. A relatively long club is highly effective in improving the flight distance by reducing the weight of the shaft. From this viewpoint, the head 4 is preferably a wood type golf club head, a hybrid type golf club head, or a utility type golf club head. The hollow head has a large moment of inertia. In a club having a large moment of inertia of the head, the effect of improving the flight distance can be stably obtained. From this viewpoint, the head 4 is preferably hollow.

  The material of the head 4 is not limited. Examples of the material of the head 4 include titanium, a titanium alloy, CFRP (carbon fiber reinforced plastic), stainless steel, maraging steel, and soft iron. Combinations of multiple materials are also possible. For example, CFRP and a titanium alloy can be combined. From the viewpoint of lowering the center of gravity of the head, a head in which at least a part of the crown is CFRP and at least a part of the sole is a titanium alloy may be used. From the viewpoint of strength, the entire face is preferably a titanium alloy.

  The shaft 6 is composed of a laminate of fiber reinforced resin layers. The shaft 6 is a tubular body. The shaft 6 has a hollow structure. As shown in FIG. 1, the shaft 6 has a tip end Tp and a butt end Bt. The chip end Tp is located inside the head 4. The butt end Bt is located inside the grip 8.

  The shaft 6 is a so-called carbon shaft. Preferably, the shaft 6 is formed by curing a prepreg sheet. In this prepreg sheet, the fibers are substantially oriented in one direction. Thus, the prepreg in which the fibers are substantially oriented in one direction is also referred to as a UD prepreg. “UD” is an abbreviation for unidirection. A prepreg other than the UD prepreg may be used. For example, the fibers contained in the prepreg sheet may be knitted. Details of the prepreg will be described later.

  The prepreg sheet has a fiber and a resin. This resin is also referred to as a matrix resin. Typically, this fiber is carbon fiber. Typically, this matrix resin is a thermosetting resin.

  The shaft 6 is manufactured by a so-called sheet winding method. In the prepreg, the matrix resin is in a semi-cured state. The shaft 6 is formed by winding and curing a prepreg sheet. This curing is to cure the semi-cured matrix resin. This curing is achieved by heating. The manufacturing process of the shaft 6 includes a heating process. By this heating step, the matrix resin of the prepreg sheet is cured.

  FIG. 2 is a development view (sheet configuration diagram) of the prepreg sheet constituting the shaft 6. The shaft 6 is composed of a plurality of sheets. In the embodiment of FIG. 2, the shaft 6 is composed of 11 sheets from s1 to s11. In the present application, the developed view shown in FIG. 2 and the like shows the sheets constituting the shaft in order from the radial inner side of the shaft. The sheets are wound in order from the sheet located on the upper side in the development view. However, when a united sheet is formed by bonding, the united sheet is wound in the state of the united sheet. In the developed view of the present application, the left-right direction of the drawing coincides with the shaft axis direction. In the developed view of the present application, the right side of the drawing is the tip end Tp side of the shaft. In the developed view of the present application, the left side of the drawing is the butt end Bt side of the shaft.

  The developed view of the present application shows not only the winding order of the sheets but also the arrangement of the sheets in the shaft axial direction. For example, in FIG. 2, the end of the sheet s1 is located at the tip end Tp. For example, in FIG. 2, the ends of the sheet s4 and the sheet s5 are located at the butt end Bt.

  The shaft 6 includes a straight layer, a bias layer, and a hoop layer. In the developed view of the present application, the orientation angle of the fiber is described. The sheet described as “0 °” constitutes the straight layer. The sheet for the straight layer is also referred to as a straight sheet in the present application.

  The straight layer is a layer in which the fiber orientation is substantially 0 ° with respect to the longitudinal direction of the shaft (shaft axis direction). Due to errors in winding, the fiber orientation may not be completely 0 ° with respect to the shaft axis direction. Usually, in the straight layer, the absolute angle θa is 10 ° or less.

  In the embodiment of FIG. 2, the straight sheets are the sheet s1, the sheet s4, the sheet s5, the sheet s6, the sheet s8, the sheet s9, the sheet s10, and the sheet s11. The straight layer has a high correlation with the bending rigidity and bending strength of the shaft.

  On the other hand, the bias layer has a high correlation with the torsional rigidity and torsional strength of the shaft. Preferably, the bias layer is composed of two sheet pairs in which fiber orientations are inclined in opposite directions. From the viewpoint of torsional rigidity, the absolute angle θa of the bias layer is preferably 15 ° or more, more preferably 25 ° or more, and further preferably 40 ° or more. From the viewpoint of torsional rigidity and bending rigidity, the absolute angle θa of the bias layer is preferably 60 ° or less, and more preferably 50 ° or less.

  In the shaft 6, the sheets constituting the bias layer are the sheet s2 and the sheet s3. FIG. 2 shows the angle Af for each sheet. The plus (+) and minus (−) at the angle Af indicate that the fibers of the bias sheet are inclined in directions opposite to each other. In the present application, the sheet for the bias layer is also simply referred to as a bias sheet.

  In the embodiment of FIG. 2, the sheet s2 is −45 degrees and the sheet s3 is +45 degrees, but conversely, the sheet s2 may be +45 degrees and the sheet s3 may be −45 degrees. Of course.

  In the shaft 6, the sheet constituting the hoop layer is a sheet s7. Preferably, the absolute angle θa in the hoop layer is substantially 90 ° with respect to the shaft axis. However, the fiber orientation may not be completely 90 ° with respect to the axial direction of the shaft due to errors in winding. Usually, in the hoop layer, the absolute angle θa is 80 ° or more and 90 ° or less. In the present application, the prepreg sheet for the hoop layer is also referred to as a hoop sheet.

  The hoop layer contributes to increasing the crushing rigidity and crushing strength of the shaft. The crushing rigidity is the rigidity against a force that crushes the shaft inward in the radial direction. The crushing strength is strength against a force that crushes the shaft toward the inside in the radial direction. The crushing strength can also be related to the bending strength. Crushing deformation can occur in conjunction with bending deformation. In particular, this linkage is large in a light-weight shaft with a thin wall thickness. The bending strength can be improved by improving the crushing strength.

  Although not shown, the prepreg sheet before being used is usually sandwiched between cover sheets. Usually, the cover sheet is a release paper and a resin film. That is, the prepreg sheet before being used is sandwiched between the release paper and the resin film. A release paper is attached to one surface of the prepreg sheet, and a resin film is attached to the other surface of the prepreg sheet. In the following, the surface on which the release paper is affixed is also referred to as “surface on the release paper side”, and the surface on which the resin film is affixed is also referred to as “surface on the film side”.

  In the developed view of the present application, the film side surface is the front side. That is, in the developed view of the present application, the front side of the drawing is the film side surface, and the back side of the drawing is the release paper side surface. For example, in FIG. 2, the fiber direction of the sheet s2 and the fiber direction of the sheet s3 are the same, but the sheet s3 is turned over at the time of bonding described later. As a result, the fiber direction of the sheet s2 and the fiber direction of the sheet s3 are opposite to each other. Therefore, in the state after being wound, the fiber direction of the sheet s2 and the fiber direction of the sheet s3 are opposite to each other. In consideration of this point, in FIG. 2, the fiber direction of the sheet s2 is expressed as “−45 °”, and the fiber direction of the sheet s3 is expressed as “+ 45 °”.

  In order to wind the prepreg sheet, first, the resin film is peeled off. When the resin film is peeled off, the film side surface is exposed. This exposed surface has tackiness (adhesiveness). This tackiness is attributed to the matrix resin. Since the matrix resin is in a semi-cured state, adhesiveness is developed. Next, the edge (also referred to as the winding start edge) of the exposed film side surface is attached to the winding object. Due to the adhesiveness of the matrix resin, the winding start edge can be smoothly attached. The wound object is a mandrel or a wound object in which another prepreg sheet is wound around the mandrel. Next, the release paper is peeled off. Next, the winding object is rotated, and the prepreg sheet is wound around the winding object. In this way, the resin film is peeled off first, then the winding start end is attached to the winding object, and then the release paper is peeled off. That is, the resin film is first peeled off, and the release paper is peeled off after the winding start edge is attached to the winding object. By this procedure, sheet wrinkling and winding defects are suppressed. This is because the sheet on which the release paper is affixed is supported by the release paper and thus is difficult to become a wrinkle. The release paper has higher bending rigidity than the resin film.

  In the embodiment of FIG. 2, a united sheet is used. The united sheet is formed by bonding two or more sheets.

  In the embodiment of FIG. 2, two united sheets are formed. FIG. 3 shows the first united sheet s23. The united sheet s23 is formed by bonding the sheet s2 and the sheet s3. FIG. 4 shows a second united sheet s78. The united sheet s78 is formed by bonding the sheet s7 and the sheet s8.

  In the combined sheet s23, the sheet s2 and the sheet s3 are shifted by a half circumference. That is, in the wound shaft, the circumferential position of the sheet s2 and the circumferential position of the sheet s3 are different in the circumferential direction. This difference angle is preferably 180 ° (± 15 °).

  As a result of using the united sheet s23, the first bias layer s2 and the second bias layer s3 are displaced from each other in the circumferential direction. Due to this deviation, the position of the end of the bias layer is dispersed in the circumferential direction. This dispersion improves the uniformity in the circumferential direction of the shaft.

  As shown in FIG. 4, in the second united sheet s78, the upper end of the sheet s7 and the upper end of the sheet s8 coincide. In the sheet s78, the entire sheet s7 is attached to the sheet s8. Therefore, the winding defect of the sheet s7 is suppressed in the winding process.

  As described above, in the present application, sheets and layers are classified according to the orientation angle of the fibers. Furthermore, in this application, a sheet | seat and a layer are classified according to the length of a shaft axial direction.

  In this application, the layer arrange | positioned to the whole shaft axial direction is called a full length layer. In this application, the sheet | seat arrange | positioned to the whole shaft axial direction is called a full length sheet | seat. The wound full length sheet forms a full length layer.

  On the other hand, in the present application, a layer partially disposed in the shaft axial direction is referred to as a partial layer. In the present application, a sheet partially disposed in the shaft axial direction is referred to as a partial sheet. The wound partial sheet forms a partial layer.

  In this application, the full length layer which is a straight layer is called a full length straight layer. In the embodiment of FIG. 2, the full length straight layers are the sheet s6, the sheet s8, and the sheet s9.

  In this application, the full length layer which is a hoop layer is called a full length hoop layer. In the embodiment of FIG. 2, the full length hoop layer is the sheet s7.

  In the present application, a partial layer that is a straight layer is referred to as a partial straight layer. In the embodiment of FIG. 2, the partial straight layers are the sheet s1, the sheet s4, the sheet s5, the sheet s10, and the sheet s11.

  The shaft 6 is manufactured by the sheet winding method using the sheet shown in FIG.

  Below, the outline of the manufacturing process of this shaft 6 is demonstrated.

[Outline of shaft manufacturing process]

(1) Cutting process In a cutting process, a prepreg sheet is cut into a desired shape. By this step, each sheet shown in FIG. 2 is cut out.

  Note that the cutting may be performed by a cutting machine or may be performed manually. In the case of manual work, for example, a cutter knife is used.

(2) Bonding step In the bonding step, a plurality of sheets are bonded. In this embodiment, the united sheet s23 and the united sheet s78 described above are produced.

  In the bonding step, heating or pressing may be used. More preferably, heating and pressing are used in combination. In the winding process described later, the sheet can be displaced during the winding operation of the united sheet. This deviation reduces the winding accuracy. Heating and pressing improve the adhesion between the sheets. Heating and pressing suppress the displacement between sheets in the winding process.

(3) Winding process In the winding process, a mandrel is prepared. A typical mandrel is made of metal. A release agent is applied to the mandrel. Further, an adhesive resin is applied to the mandrel. This resin is also called a tacking resin. The cut sheet is wound around the mandrel. With this tacking resin, it is easy to attach the end of the sheet to the mandrel.

  Regarding the sheet | seat which concerns on bonding, it winds in the state of a united sheet.

  By this winding step, a wound body is obtained. This wound body is formed by winding a prepreg sheet around the mandrel. The winding is performed, for example, by rolling the winding object on a plane. This winding may be performed manually or by a machine. This machine is called a rolling machine.

(4) Tape wrapping step In the tape wrapping step, a tape is wound around the outer peripheral surface of the wound body. This tape is also called a wrapping tape. The wrapping tape is wound while being applied with tension. The wrapping tape is wound spirally at a predetermined pitch. The wrapping tape applies pressure to the wound body. This pressure reduces voids.

(5) Curing process In the curing process, the wound body after tape wrapping is heated. By this heating, the matrix resin is cured. During this curing process, the matrix resin is temporarily fluidized. By fluidizing the matrix resin, air between sheets or in sheets can be discharged. This air discharge is promoted by the pressure (tightening force) of the wrapping tape. By this curing, a cured laminate is obtained.

(6) Mandrel extraction step and wrapping tape removal step After the curing step, a mandrel extraction step and a wrapping tape removal step are performed. Although the order of both is not limited, from the viewpoint of improving the efficiency of the wrapping tape removal process, the wrapping tape removal process is preferably performed after the mandrel pulling process.

(7) Both-ends cutting process In this process, the both ends of a hardening laminated body are cut. By this cutting, the end surface of the tip end Tp and the end surface of the butt end Bt are made flat.

(8) Polishing step In this step, the surface of the cured laminate is polished. On the surface of the cured laminate, there are spiral irregularities left as traces of the wrapping tape. By polishing, the irregularities as traces of the wrapping tape disappear, and the surface is smoothed.

(9) Painting process Coating is applied to the cured laminate after the polishing process.

  The head 4 and the grip 8 are attached to the shaft 6 manufactured in this way, and the golf club 2 is obtained.

  The circle in FIG. 5 is an enlarged view of the cross section of the shaft 6. FIG. 5 is a cross-sectional view of the shaft 6 at the center position in the longitudinal direction. FIG. 5 shows a portion where only the full length sheet exists.

  In the shaft 6, the bias sheet s2 is 2 plies, and the bias sheet s3 is also 2 plies. Therefore, a total of four bias layers are formed.

  In the shaft 6, the full length straight sheet s6 is one ply. Therefore, one full length straight layer s6 is formed.

  In the shaft 6, the full length hoop sheet s7 is one ply. Therefore, one full length hoop layer s7 is formed.

  In the shaft 6, the full length straight sheet s8 is 2 plies. Therefore, two full length straight layers s8 are formed.

  In the shaft 6, the full length straight sheet s9 is 2 plies. Therefore, two full length straight layers s9 are formed. One outer layer of the two full length straight layers s9 is the outermost full length straight layer s100.

  The shaft 6 includes a novolac-containing layer. The novolac-containing layer is a layer in which the matrix resin contains a novolac type epoxy resin.

  In the shaft 6, the sheet s8, the sheet s9, the sheet s10, and the sheet s11 are novolak-containing layers. All the straight layers located outside the hoop layer s7 are novolak-containing layers.

  In the shaft 6, the full length straight layers s8 and s9 located outside the full length bias layers s2 and s3 are novolac-containing layers. The full length straight layers s8 and s9 located on the outside effectively increase the strength of the shaft.

  In the shaft 6, the partial straight layers s10 and s11 positioned outside the full length straight layers s8 and s9, which are novolak-containing layers, are novolak-containing layers. When the partial straight layers s10 and s11 that are located outside and reinforce the tip are made novolak-containing layers, the strength of the tip of the shaft is effectively increased. In the shaft 6, the partial straight layer s11 that is located on the outermost side and reinforces the tip is a novolac-containing layer. Therefore, the strength of the tip portion of the shaft is increased.

  In the novolac-containing layers s8, s9, s10, and s11, the content Rn of the novolac-type epoxy resin in the matrix resin is 3% by mass or more and 19% by mass or less. It was found that this numerical range contributes to the improvement of the shaft strength.

  In the present application, the average specific gravity of the novolak-containing layer constituting the full length straight layer is S1, and the average specific gravity of the full length bias layer and the inner layer of the full length bias layer is S2. The target layer for the specific gravity S2 is the full length bias layer and the inner layer, and it does not matter whether it is a novolac-containing layer. In the shaft 6, the specific gravity S1 is larger than the specific gravity S2. In the shaft 6, the novolac-containing layer constituting the full length straight layer is a total of four layers of the layer s 8 (two layers) and the layer s 9 (two layers) (see FIG. 5).

  When the fiber is increased and the matrix resin is decreased, the specific gravity of the layer increases. In this case, since there is little resin, the adhesiveness between layers tends to fall. Delamination between layers can reduce the strength of the shaft. However, by including a novolac type epoxy resin in a layer having a large specific gravity, a decrease in shaft strength in the layer having a high specific gravity is suppressed. Moreover, the strength improvement effect A and the strength improvement effect B can be produced synergistically by disposing the novolac-containing layer having a high fiber content on the outside. The strength improving effect A is a strength improving effect due to the novolac type epoxy resin, and the strength improving effect B is a strength improving effect due to an increase in the amount of fibers. Bending failure often occurs from the outside of the shaft. The strength improvement effect A and the strength improvement effect B are enhanced by the outward arrangement.

  By making the specific gravity S1 larger than the specific gravity S2, it becomes possible to arrange a prepreg having a low specific gravity inside. Therefore, the inner layer of the shaft is reduced in weight, and the shaft weight is also reduced. On the other hand, since specific gravity S1 is large, the fiber content rate of the layer located relatively outside can be increased. Therefore, the shaft strength is improved. Furthermore, since the layer having this high specific gravity S1 is the novolac-containing layer nv1, the strength improvement effect due to the fiber content and the strength improvement effect due to the novolac resin are synergistically exhibited.

  By arranging the novolac-containing layer nv1 having a high specific gravity S1 on the outside, the moment of inertia of the shaft around the shaft axis increases. This improvement in moment of inertia can contribute to the directional stability of the hit ball. Further, the novolac-containing layer nv1 having a high specific gravity S1 is arranged on the outside, so that the specific gravity on the outer side of the shaft is higher than the specific gravity on the inner side of the shaft. Therefore, the vibration damping rate of the shaft can be improved. This improvement in vibration damping rate can improve the hitting ball feeling. From these viewpoints, the specific gravity Sx1 in the outer region X1 of the shaft is preferably higher than the specific gravity Sx2 in the inner region X2 of the shaft. The outer region X1 of the shaft means a region outside the boundary surface kc that bisects the thickness of the shaft (see FIG. 5). The inner region X2 of the shaft means a region inside the boundary surface kc that bisects the thickness of the shaft (see FIG. 5).

  In FIG. 5, what is indicated by a double-headed arrow Tn is the total thickness of the novolac-containing layer nv1 located at the outermost part of the shaft. This thickness Tn is defined in a portion where only the full length layer exists. In light of shaft strength, the thickness Tn is preferably equal to or greater than 0.1 mm, more preferably equal to or greater than 0.2 mm, and still more preferably equal to or greater than 0.3 mm. In light of weight reduction, the thickness Tn is preferably equal to or less than 0.8 mm, more preferably equal to or less than 0.7 mm, and still more preferably equal to or less than 0.6 mm.

  The shaft 6 has an outermost full length straight layer s100. This outermost full length straight layer s100 is a novolac-containing layer. With this configuration, the strength of the shaft 6 is effectively increased. The outermost full length straight layer s100 is a straight layer located on the outermost side among the full length layers.

  In the shaft 6, the outermost N layer among the full length straight layers is the novolac-containing layer nv 1. In the shaft 6, of the full length straight layers, the layer s8 and the layer s9 are the novolac-containing layer nv1. For this reason, in the shaft 6, the four outermost layers among the full length straight layers are the novolac-containing layer nv <b> 1 (see FIG. 5). That is, in the shaft 6, the above N is 4. With this configuration, the strength of the shaft 6 is effectively increased. From the viewpoint of shaft strength, N is preferably 2 or more, more preferably 3 or more, and still more preferably 4 or more. From the viewpoint of reducing the weight of the shaft, N is preferably 8 or less, more preferably 7 or less, and even more preferably 6 or less.

  In the shaft 6, all the novolac-containing layers nv1 are straight layers. The straight layer greatly contributes to the bending strength of the shaft. By making all the novolac-containing layers nv1 into straight layers, the shaft strength is effectively increased.

  In the shaft 6, M full-length straight layers that are novolac-containing layers nv <b> 1 are provided. In the shaft 6, this M is 4. As shown in FIG. 5, in the shaft 6, all of these M layers are located on the outermost side of the full length layers. With this configuration, the shaft strength is effectively increased. From the viewpoint of shaft strength, M is preferably 2 or more, more preferably 3 or more, and still more preferably 4 or more. From the viewpoint of reducing the weight of the shaft, M is preferably 8 or less, more preferably 7 or less, and even more preferably 6 or less.

In the shaft 6, the fiber elastic modulus Y1 in the novolac-containing layer nv1 is 8 t / mm ² or more and less than 38 t / mm ² . In the shaft 6, the fiber elastic modulus Y10 in the novolac-containing layer nv1 located outside the full length bias layer is 8 t / mm ² or more and less than 38 t / mm ² . In the shaft 6, the fiber elastic modulus Y2 in the full length straight layer other than the novolac-containing layer is 38 t / mm ² or more and 70 t / mm ² or less. In the shaft 6, the fiber elastic modulus Y3 in the full length bias layer is 38 t / mm ² or more and 70 t / mm ² or less.

By setting the fiber elastic modulus Y1 to 8 t / mm ² or more and less than 38 t / mm ² , the shaft strength is effectively increased. The combination of a relatively high strength fiber and a novolac type epoxy resin effectively increases the shaft strength. Further, since the novolac-containing layer nv1 is disposed relatively outside, the shaft strength is further increased. More preferably, the fiber elastic modulus Y1 is 8 t / mm ² or more and 30 t / mm ² or less.

By setting the fiber elastic modulus Y10 to 8 t / mm ² or more and less than 38 t / mm ² , the shaft strength is effectively increased. The combination of a relatively high strength fiber and a novolac type epoxy resin effectively increases the shaft strength. Further, since the novolac-containing layer nv1 is disposed relatively outside, the shaft strength is further increased. More preferably, the fiber elastic modulus Y10 is 8 t / mm ² or more and 30 t / mm ² or less.

By fiber modulus Y2 is a 38 t / mm ² or more 70 t / mm ² or less, while reducing the amount of fibers, it is possible to increase the flexural rigidity. Therefore, weight reduction can be achieved while ensuring the required flex.

By fiber modulus Y3 is a 38 t / mm ² or more 70 t / mm ² or less, while reducing the amount of fibers, it is possible to increase the torsional rigidity. Therefore, weight reduction can be achieved while ensuring the required torque.

As shown in FIG. 5, the full length novolak-containing layer nv1 located on the innermost side is the innermost novolak-containing layer nv2. In the shaft 6, the fiber elastic modulus Y4 in the full length layer located inside the innermost novolac-containing layer nv2 is 38 t / mm ² or more and 70 t / mm ² or less. With this configuration, it is possible to increase the rigidity while reducing the amount of fibers. Therefore, weight reduction can be achieved while ensuring the required torque and / or flex. Moreover, shaft strength can be raised by arrange | positioning the highly elastic layer with comparatively low intensity | strength inside. The full length novolac-containing layer is a full length novolac-containing layer.

In the shaft 6, the fiber elastic modulus Y5 of the full length bias layer and the layer located inside thereof is 38 t / mm ² or more and 70 t / mm ² or less. With this configuration, it is possible to increase the rigidity while reducing the amount of fibers. Therefore, weight reduction can be achieved while ensuring the required torque and / or flex. Moreover, shaft strength can be raised by arrange | positioning the highly elastic layer with comparatively low intensity | strength inside.

[Matrix resin]
As the matrix resin, an epoxy resin composition is preferable. This epoxy resin composition preferably contains, as an epoxy resin component, an epoxy resin having two epoxy groups in the molecule, that is, a bifunctional epoxy resin. Specific examples of the bifunctional epoxy resin include bisphenol A type epoxy resin and hydrogenated product thereof, bisphenol F type epoxy resin and hydrogenated product thereof, bisphenol S type epoxy resin, tetrabromobisphenol A type epoxy resin, and bisphenol AD type epoxy. Examples thereof include bisphenol type epoxy resins such as resins. Bisphenol type epoxy resins may be used alone or in admixture of two or more.

  When a bisphenol type epoxy resin is used, it is preferable that a bisphenol A type epoxy resin and a bisphenol F type epoxy resin are used in combination. This combined use can improve the bending strength of the shaft. The content ratio of the bisphenol A type epoxy resin and the bisphenol F type epoxy resin is preferably 20:80 to 80:20, more preferably 30:70 to 70:30, and even more preferably 40:60 to 60:40 in terms of mass ratio. preferable.

  The epoxy equivalent (g / eq) of the bisphenol type epoxy resin is preferably 200 or more, more preferably 250 or more, preferably 400 or less, and more preferably 350 or less. If the epoxy equivalent of the bisphenol-type epoxy resin is less than 200, the epoxy resin component becomes liquid at room temperature, which may make it difficult to produce or mold the prepreg. On the other hand, if the epoxy equivalent is greater than 400, the epoxy resin component may become solid at room temperature, making molding difficult.

  As the bisphenol A type epoxy resin, jER827, jER828, jER1001, jER1002, jER1003, jER1003F, jER1004, jER1004FS, jER1004F, jER1004AF, jER1055, jER1005F, jER1007F, jER1007, jER1007 It is done. “JER” is a registered trademark.

  As other bisphenol A type epoxy resins, Etototo YD-011, Etototo YD-012, Etototo YD-013, Etototo YD-014, Etototo YD-017, Etototo YD-019, Etototo YD-020N, manufactured by Toto Kasei Co., Ltd. And Epototo YD-020H. “Epototo” is a registered trademark.

  Examples of other bisphenol A type epoxy resins include Epicron 1050, Epicron 3050, Epicron 4050 and Epicron 7050 manufactured by DIC Corporation. “Epiclon” is a registered trademark. As other bisphenol A type epoxy resins, EP-5100, EP-5400, EP-5700, EP-5900 (manufactured by ADEKA), DER-661, DER-663U, DER-664, DER-667, DER- 668, DER-669 (above, manufactured by Dow Chemical Co., Ltd.).

  Examples of the bisphenol F type epoxy resin include jER806, jER807, jER4005P, jER4007P, jER4010P (above, manufactured by Mitsubishi Chemical Corporation).

  The epoxy resin composition preferably contains a polyfunctional epoxy resin having 3 or more epoxy groups in the molecule in addition to the epoxy resin having 2 epoxy groups in the molecule. By containing a polyfunctional epoxy resin, the crosslinking density of the cured product of the epoxy resin composition can be controlled. It is considered that the interfacial strength between the reinforcing fiber and the epoxy resin is improved by controlling the crosslinking density and setting the elongation of the cured product of the epoxy resin composition within an appropriate range.

  Although it does not specifically limit as a polyfunctional epoxy resin, Novolac type epoxy resins, such as a phenol novolak type epoxy resin and o-cresol novolak type epoxy resin; Triglycidyl ether of tris (p-hydroxyphenyl) methane, its derivative, tetrakis ( p-hydroxyphenyl) ethane tetraglycidyl ether and derivatives thereof, glycerin triglycidyl ether, pentaerythritol tetraglycidyl ether and other glycidyl ether-based epoxy resins; tetraglycidyl diaminodiphenylmethane, tetraglycidyl m-xylylenediamine, triglycidyl- Examples thereof include glycidylamine epoxy resins such as m-aminophenol.

  A preferred polyfunctional epoxy resin is a novolac type epoxy resin. Examples of the novolac type epoxy resin include phenol novolac type epoxy resin and o-cresol novolac type epoxy resin. From the viewpoint of the strength of the cured resin, the content ratio Rn of the novolac type epoxy resin in the epoxy resin component is preferably 3% by mass or more, more preferably 4% by mass or more, more preferably 5% by mass or more, and 7% by mass. The above is more preferable, 19 mass% or less is preferable, 14 mass% or less is more preferable, 13 mass% or less is more preferable, and 11 mass% or less is further more preferable.

  The epoxy equivalent (g / eq) of the polyfunctional epoxy resin is preferably 50 or more, more preferably 75 or more, further preferably 100 or more, preferably 500 or less, more preferably 400 or less, and further preferably 300 or less. When the epoxy equivalent of the polyfunctional epoxy resin is within the above range, a crosslinked structure can be effectively formed.

  Commercially available phenol novolac epoxy resins include jER152 and jER154 (manufactured by Mitsubishi Chemical Corporation), Epicron N-740, Epicron N-770 and Epicron N-775 (manufactured by DIC Corporation), PY307, EPN1179. EPN 1180 (manufactured by Huntsman Advanced Material), YDPN638 and YDPN638P (manufactured by Toto Kasei), DEN431, DEN438 and DEN439 (manufactured by Dow Chemical), EPR600 (manufactured by Bakerite), EPPN -201 (manufactured by Nippon Kayaku Co., Ltd.).

  The epoxy resin composition preferably contains a curing agent. Examples of the curing agent include dicyandiamide; active hydrogen such as 4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenylsulfone, 3,3′-diaminodiphenylsulfone, m-phenylenediamine, and m-xylylenediamine. Aromatic amines having; active amines such as diethylenetriamine, triethylenetetramine, isophoronediamine, bis (aminomethyl) norbornane, bis (4-aminocyclohexyl) methane, dimer acid ester of polyethyleneimine; these activities Modified amines obtained by reacting hydrogen-containing amines with compounds such as epoxy compounds, acrylonitrile, phenol and formaldehyde, thiourea; dimethylaniline, triethylenediamine, dimethylbenzylamine, 2, Tertiary amines having no active hydrogen such as 1,6-tris (dimethylaminomethyl) phenol; imidazoles such as 2-methylimidazole and 2-ethyl-4-methylimidazole; polyamide resin; hexahydrophthalic anhydride, Carboxylic anhydrides such as tetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, methyl nadic acid anhydride; polycarboxylic acid hydrazides such as adipic acid hydrazide and naphthalenedicarboxylic acid hydrazide; polyphenol compounds such as novolac resin; Polymercaptans such as esters of thioglycolic acid and polyols; Lewis acid complexes such as boron trifluoride ethylamine complexes can be used. Among these, it is preferable to use dicyandiamide as a curing agent.

  The amount of dicyandiamide added is preferably 13 g or more, more preferably 15 g or more, further preferably 17 g or more, preferably 40 g or less, preferably 38 g or less, and more preferably 35 g or less, per 1 mol of the epoxy group of the epoxy resin component. . When the amount of dicyandiamide added is in the above range, the mechanical properties of the cured product of the epoxy resin composition will be good.

  An appropriate curing aid can be combined with the curing agent to increase the curing activity. As the curing aid, a urea derivative in which at least one of hydrogen bonded to urea is substituted with a hydrocarbon group is preferable. The hydrocarbon group may be further substituted with, for example, a halogen atom, a nitro group, or an alkoxy group. Examples of the urea derivative include 3-phenyl-1,1-dimethylurea, 3- (parachlorophenyl) -1,1-dimethylurea, 3- (3,4-dichlorophenyl) -1,1-dimethylurea, 3 -(Orthomethylphenyl) -1,1-dimethylurea, 3- (paramethylphenyl) -1,1-dimethylurea, 3- (methoxyphenyl) -1,1-dimethylurea, 3- (nitrophenyl)- Derivatives of monourea compounds such as 1,1-dimethylurea; and N, N-phenylene-bis (N ', N'-dimethylurea), N, N- (4-methyl-1,3-phenylene)- Examples thereof include derivatives of bisurea compounds such as bis (N ′, N′-dimethylurea). Examples of preferred combinations include dicyandiamide, 3-phenyl-1,1-dimethylurea, 3- (3,4-dichlorophenyl) -1,1-dimethylurea (DCMU), 3- (3-chloro-4- Examples include combining urea derivatives such as methylphenyl) -1,1-dimethylurea and 2,4-bis (3,3-dimethylureido) toluene as curing aids. Among these, it is more preferable to combine dicyandiamide with 3- (3,4-dichlorophenyl) -1,1-dimethylurea (DCMU) as a curing aid.

  It is preferable to use dicyandiamide (DICY) as a curing agent and a urea derivative as a curing aid. In this case, the content ratio of dicyandiamide (DICY) and the urea derivative is preferably 1 or more, more preferably 1.2 or more, more preferably 1.5 or more, and more preferably 3 or less in terms of mass ratio (DICY / urea derivative). 2.8 or less is more preferable, and 2.5 or less is more preferable. The mass ratio (DICY / urea derivative) is most preferably 2. If the mass ratio of DICY / urea derivative is within the above range, the curing rate is fast and the cured product has good physical properties.

  The epoxy resin composition may further contain other components such as oligomers, polymer compounds, organic or inorganic particles.

  As an oligomer that can be blended in the epoxy resin composition used in the present invention, a polyester polyurethane having a polyester skeleton and a polyurethane skeleton, a urethane having a polyester skeleton and a polyurethane skeleton, and further having a (meth) acrylate group at the molecular chain terminal (meta) ) Acrylates, indene oligomers and the like.

  A thermoplastic resin is suitably used as the polymer compound that can be blended in the epoxy resin composition. By blending a thermoplastic resin, the effect of controlling the viscosity of the resin, the handling property of the prepreg sheet, or improving the adhesiveness is preferably increased.

  Examples of this thermoplastic resin include polyvinyl acetal resins such as polyvinyl formal and polyvinyl butyral, polyvinyl alcohol, and phenoxy resin. This thermoplastic resin may have an amide bond or a sulfonyl group. Examples of the thermoplastic resin having an amide bond include polyamide and polyimide. Examples of the thermoplastic resin having a sulfonyl group include polysulfone. Polyamide, polyimide and polysulfone may have a functional group such as an ether bond and a carbonyl group in the main chain. The polyamide may have a substituent on the nitrogen atom of the amide group. The epoxy resin composition used in the present invention preferably contains polyvinyl formal as a thermoplastic resin.

  The content ratio of this thermoplastic resin is preferably 2 parts by mass or more, more preferably 3 parts by mass or more, further preferably 4 parts by mass or more, and preferably 12 parts by mass or less, relative to 100 parts by mass of the epoxy resin component. Less than the mass part is more preferable. If the content ratio of the thermoplastic resin is 2 parts by mass or more, the elongation of the epoxy resin composition is improved and tack can be imparted. On the other hand, when the content ratio of the thermoplastic resin exceeds 12 parts by mass, the epoxy resin composition may be solidified at room temperature. Therefore, the impregnation property to the reinforcing fiber is lowered, and a void may be caused at the time of producing the prepreg.

  Rubber particles and thermoplastic resin particles can be used as the organic particles that can be blended in the epoxy resin composition. These particles have the effect of improving the toughness of the resin and improving the impact resistance of the fiber-reinforced composite material. As the rubber particles, cross-linked rubber particles and core-shell rubber particles obtained by graft polymerization of a different polymer on the surface of the cross-linked rubber particles are preferably used.

  As commercially available crosslinked rubber particles, XER-91 (manufactured by Nippon Synthetic Rubber Industry) comprising a crosslinked product of a carboxyl-modified butadiene-acrylonitrile copolymer, CX-MN series (manufactured by Nippon Shokubai Co., Ltd.) comprising acrylic rubber fine particles, YR-500 series (manufactured by Toto Kasei Co., Ltd.) or the like can be used. Commercially available core-shell rubber particles include paraloid EXL-2655 (manufactured by Kureha Chemical Co., Ltd.) made of butadiene / alkyl methacrylate / styrene copolymer, staphyloid AC-3355 made of acrylic ester / methacrylic ester copolymer, TR-2122 (manufactured by Takeda Pharmaceutical Co., Ltd.), PARALOIDEXL-2611, EXL-3387 (registered trademark, trade name, manufactured by Rohm & Haas) made of butyl acrylate / methyl methacrylate copolymer can be used. .

  As the thermoplastic resin particles, polyamide or polyimide particles are preferably used. As commercially available polyamide particles, trade name “SP-500” manufactured by Toray Industries, Inc., “Orgasol” (registered trademark) manufactured by ATOCHEM, and the like can be used.

  As inorganic particles that can be blended in the epoxy resin composition, silica, alumina, smectite, synthetic mica and the like can be blended. These inorganic particles are blended mainly for rheology control, that is, for thickening and thixotropic imparting.

  The tensile strength (breaking strength) of the cured product of the epoxy resin composition is preferably 20 MPa or more, more preferably 30 MPa or more, further preferably 50 MPa or more, preferably 500 MPa or less, more preferably 450 MPa or less, and further preferably 400 MPa or less. Further, the elongation (breaking elongation) of the cured product of the epoxy resin composition is preferably 2% or more, more preferably 3% or more, preferably 300% or less, and more preferably 100% or less. The measuring method of tensile strength and elongation will be described later.

  The resin component of the matrix resin is preferably composed only of the epoxy resin composition, but a commercially available epoxy resin composition may be used in combination as long as the effects of the present invention are not impaired. When a commercially available epoxy resin composition is used in combination, the content of the commercially available epoxy resin composition in the resin component of the matrix resin is preferably 95% by mass or less, more preferably 90% by mass or less, and further 80% by mass or less. preferable.

  The swelling ratio of the cured epoxy resin composition with methyl ethyl ketone is preferably 20% by mass or more, more preferably 25% by mass or more, preferably 42.5% by mass or less, and more preferably 38% by mass or less. This swelling rate with methyl ethyl ketone indicates the degree of crosslinking of the cured product of the epoxy resin composition. When the swelling ratio is 20% by mass to 42.5% by mass, a more appropriate crosslinking density can be obtained. With this crosslink density, an appropriate elongation for improving the interfacial strength can be obtained.

  Examples of the reinforcing fiber include carbon fiber, glass fiber, aramid fiber, boron fiber, alumina fiber, and silicon carbide fiber. Also, two or more of these fibers can be mixed. A preferred reinforcing fiber is carbon fiber.

  Examples of the carbon fiber include PAN-based, pitch-based, and rayon-based carbon fibers, and PAN-based carbon fibers are preferable from the viewpoint of tensile strength. As for the form of carbon fiber, carbon fiber obtained by twisting and firing the precursor fiber (so-called twisted yarn), carbon fiber obtained by untwisting the twisted yarn (so-called untwisted yarn), and substantially the precursor fiber Non-twisted yarns that are heat-treated without twisting them can be used. In consideration of the balance between moldability and strength characteristics of the fiber-reinforced composite material, non-twisted yarn or untwisted yarn is preferable. Further, non-twisted yarn is preferable from the viewpoint of handling properties such as adhesion between prepreg sheets. Carbon fibers can also include graphite fibers.

The tensile modulus of the reinforcing fibers is preferably from 10t / mm ² or more, more preferably 24t / mm ² or more, preferably 70 t / mm ² or less, more preferably 50t / mm ^2. The tensile elastic modulus is measured in accordance with JIS R 7601: 1986 “Carbon Fiber Test Method”. If the tensile modulus of the reinforcing fiber is within the above range, the bending strength can be improved.

  The content of the reinforcing fiber in the shaft is preferably 65% by mass or more, more preferably 70% by mass or more, preferably 80% by mass or less, and more preferably 75% by mass or less. If the content rate of a reinforced fiber exists in the said range, it can become a favorable fiber reinforced epoxy resin material which can fully utilize the high intensity | strength of resin.

  A known method is used for manufacturing the shaft. For example, a prepreg obtained by impregnating a reinforcing fiber such as carbon fiber with the epoxy resin composition is prepared, cut into the shape of each material constituting the shaft, and after lamination, pressure is applied while heating the laminate. The method of doing can be mentioned. A specific example of this method is as described above for the method of manufacturing the shaft 6.

  The prepreg can be manufactured by a wet method, a hot melt method, or the like. In the wet method, the reinforcing fiber is impregnated with an epoxy resin composition that has been dissolved in a solvent such as methyl ethyl ketone or methanol to reduce the viscosity. In the hot melt method, the reinforcing fiber is impregnated with an epoxy resin composition whose viscosity is reduced by heating.

  In the wet method, the reinforcing fiber is dipped in a solution made of an epoxy resin composition and then pulled up, and the solvent is evaporated while heating using an oven or the like to obtain a prepreg. There are two hot melt methods. The first method is a method of directly impregnating reinforcing fibers with an epoxy resin composition whose viscosity has been reduced by heating. In the second method, a film in which an epoxy resin composition is once coated on release paper or the like is prepared, and then the film is laminated from both sides or one side of the reinforcing fiber and heated to heat the epoxy resin composition. Impregnate into a prepreg. The hot melt method is preferable because the solvent does not substantially remain in the prepreg.

  Examples of methods for applying pressure while heating the prepreg laminate include a wrapping tape method and an internal pressure molding method. The wrapping tape method is a method of obtaining a molded body by winding a prepreg around a mandrel or other core metal. Specifically, a prepreg is wound around a mandrel, a wrapping tape made of a thermoplastic resin film is wound around the outside of the prepreg for fixing and applying pressure, and the resin is heated and cured in an oven. This is a method for removing the slag to obtain a tubular molded body. The surface of the tubular molded body may be cut and painted or the like.

  In the internal pressure molding method, a prepreg is wound around an internal pressure applying body such as a tube made of a thermoplastic resin to form a preform, which is then placed in a mold, and then a high pressure gas is introduced into the internal pressure applying body to increase the pressure. It is a method of molding by heating and mold.

  Examples of the form of the reinforcing fiber in the prepreg include long fibers aligned in one direction, bi-directional woven fabric, multiaxial woven fabric, non-woven fabric, mat, knit, braided string, and the like. Here, the long fiber means a single fiber or a fiber bundle substantially continuous for 10 mm or more. A so-called unidirectional prepreg using long fibers aligned in one direction has a high fiber strength direction and a high strength utilization rate in the fiber direction because the fibers are less bent. Moreover, a unidirectional prepreg (UD prepreg) can laminate | stack a several prepreg appropriately so that the arrangement direction of a reinforced fiber may differ. Therefore, it becomes easy to design the elastic modulus and strength in each direction.

  Hereinafter, the effects of the present invention will be clarified by examples. However, the present invention should not be construed in a limited manner based on the description of the examples.

[Carbon fiber]
Carbon fiber was used as a material for producing the prepreg. The specifications of the carbon fiber are shown in Table 1 below.

[Matrix resin]
A matrix resin was produced as a material for producing the prepreg. Raw materials were blended as shown in Table 2 below to obtain eight types of matrix resin compositions R1 to R8. The composition and specifications of each matrix resin are shown in Table 2 below.

[Preparation of prepreg]
A prepreg was prepared using the carbon fiber and the matrix resin composition. These matrix resin compositions were dissolved in methyl ethyl ketone to prepare a MEK solution of an epoxy resin. The MEK content of this MEK solution was 30% by mass. A curing agent and a curing aid were added to the obtained MEK solution and stirred to prepare an epoxy resin composition solution. This epoxy resin composition solution was applied to a release paper and dried to obtain an epoxy resin composition sheet. Using a hot melt method, the sheet made of the carbon fiber was impregnated with the epoxy resin composition sheet to obtain prepregs P1 to P12. The specifications of these prepregs are shown in Tables 3 and 4 below.

[Evaluation method]

[Preparation of resin tensile test piece and test piece for methyl ethyl ketone swelling test]
The matrix resin composition was dissolved in methyl ethyl ketone to prepare an MEK solution of epoxy resin. The MEK content of this MEK solution was 30% by mass. The MEK solution was dried, heated and melted, and a curing agent and a curing aid were added and stirred. The obtained epoxy resin composition was poured into a casting mold having a thickness of 2 mm, and cured at 130 ° C. for 2 hours. A test piece for tensile test was molded from the cured resin plate according to JIS-K7162 test piece 1BA. Further, a 2 cm × 2 cm square test piece was cut out from the resin plate and used as a test piece for methyl ethyl ketone swelling test.

[Test specimen for tensile test of fiber-reinforced epoxy resin material]
The matrix resin composition was dissolved in methyl ethyl ketone to prepare an MEK solution of epoxy resin. The MEK content of this MEK solution was 30% by mass. The MEK solution, a curing agent and a curing aid were added and stirred to prepare an epoxy resin composition solution. This epoxy resin composition solution was applied to release paper and dried at 80 to 90 ° C. for 3 minutes to obtain an epoxy resin composition sheet. A carbon fiber sheet having a basis weight of 100 g was impregnated with the obtained epoxy resin composition sheet by a hot melt method to obtain a prepreg having a carbon fiber content of 70% by mass. The obtained prepreg was cut to obtain a laminate in which 10 sheets were laminated with the fiber orientation aligned in one direction. This laminate was sandwiched between release sheets having a thickness of 0.1 mm and pressed under the conditions of 80 ° C. × 30 minutes + 130 ° C. × 2 hours using a 1 mm spacer. The epoxy resin was cured by this pressing and heating to obtain a fiber reinforced epoxy resin material sheet. This fiber-reinforced epoxy resin material sheet was cut so that the length in the fiber vertical direction was 100 mm and the width in the fiber direction was 10 mm to obtain a test piece for a tensile test.

[Production of pipes]
Using the prepregs P1 to P12, pipes were produced and produced by a sheet winding method. FIG. 6 is a development view showing the laminated structure of the pipes. As shown in FIG. 6, the prepregs s1 to s88 were wound around a core metal (mandrel) in order. The prepreg s1 constitutes the innermost layer, and the prepreg s8 constitutes the outermost layer. The prepregs s1, s4, s5, s7, and s8 constitute a straight layer. The prepregs s2 and s3 constitute a bias layer. The prepreg s6 constitutes a hoop layer. As shown in FIG. 7, the prepreg s2 and the prepreg s3 were bonded together to obtain a combined sheet. Moreover, the prepreg s5 and the prepreg s6 were bonded together to obtain a combined sheet. The sheet | seat which concerns on these bonding was wound in the state of the united sheet. In addition, as prepreg s6, a commercially available prepreg (Toray Co. prepreg P805S-3 manufactured by Toray Industries, Inc.) was used. A wrapping tape was wound around the outer peripheral surface of the obtained wound body, and the curing process was performed by heating. The winding conditions and curing conditions are shown below. In addition, the unit of the dimension described in FIG.6 and FIG.7 is mm.

-Winding condition: Rolling speed: 34Hz
-Wrapping tape: PT-30H manufactured by Shin-Etsu Chemical Co., Ltd., tension 6000 ± 100 gf
・ Pitch: 2.0mm
・ Spindle speed: 1870-1890Hz
・ Curing conditions:
(1) Temperature rise from room temperature to 80 ° C in 30 minutes (2) Hold at 80 ° C ± 5 ° C for 30 minutes ± 5 minutes (3) Temperature rise from 80 ° C to 130 ° C in 30 minutes (4) 130 ° C ± 5 ° C Hold for 120 minutes ± 5 minutes.

  By changing the prepreg sheet, pipes 1 to 25 were produced. For example, in the pipe 1, the sheets s1 to s5 are prepregs P1, the sheet s6 is “P805S-3”, and the sheets s7 and s8 are prepregs P1. The specifications and evaluation results of these pipes are shown in Table 5, Table 6 and Table 7 below.

  In the pipes 23 and 24, commercially available prepreg A was used for the prepregs s7 and s8. In the pipe 25, commercially available prepreg A was used for the prepregs s4, s5, s7, and s8. This prepreg A was named “P2253S-10” manufactured by Toray Industries, Inc. This P2253S-10 has a carbon fiber of T800SC and a resin content of 30% by mass.

[Methyl ethyl ketone swelling test]
The test piece for swelling test of methyl ethyl ketone was immersed in 100 mL of methyl ethyl ketone and held at 40 ° C. for 48 hours. The mass of the test piece before and after immersion was measured. The methyl ethyl ketone swelling ratio was calculated as follows.
Swell rate = 100 × [m1−m2] / m2
However, m1 is the mass of the test piece after the swelling test, and m2 is the mass of the test piece before the swelling test.

[Tensile test]
3A and 3B show a tensile test method for a cured product of the epoxy resin composition. FIG.3 (c) shows the method of the tension test of a fiber reinforced epoxy resin material. These tensile tests were performed at a tensile speed of 1 mm / min using a Shimadzu autograph manufactured by Shimadzu Corporation.

  Fig.3 (a) is explanatory drawing which shows typically the tension test method about the test piece 12 which consists of hardened | cured material of an epoxy resin composition. FIG. 3B is a side view of the chuck 10 that grips the test piece 12 of FIG. In addition, although the unevenness | corrugation for slip prevention is provided inside the chuck | zipper 10, this unevenness | corrugation is not illustrated in FIG.3 (b). FIG.3 (c) is explanatory drawing which shows typically the tension test method about a fiber reinforced epoxy resin material. 3A and 3C, the arrow direction is the direction of the tensile test. As shown in FIG. 3C, an aluminum tag 14 was attached to a test piece 15 made of a fiber reinforced epoxy resin material. A cyanoacrylate adhesive was used for this attachment. The dimensions of the aluminum tag 14 were 4 mm in length, 1.5 mm in width, and 0.5 mm in thickness. The test was performed by pulling the test piece 15 in a direction perpendicular to the orientation direction of the reinforcing fibers 16 (90 degrees).

  The strength of the cured product of the epoxy resin composition was expressed by maximum stress × elongation at that time / 2 (MPa ·%). The results are shown in Table 2 above. The strength of the fiber reinforced epoxy resin material is indicated by the maximum stress (MPa). The results are shown in Table 2 above.

[Three point bending strength]
The three-point bending strength was performed according to the SG type three-point bending strength test. Shimadzu Autograph manufactured by Shimadzu Corporation was used as a measuring device. FIG. 9 shows a method for measuring the three-point bending strength. As shown in FIG. 9, while supporting the pipe 20 from below at the two support points e1 and e2, a load F was applied from above to below at the load point e3. The position of the load point e3 was a position where the support point e1 and the support point e2 were equally divided. The load point e3 is a measurement point. The moving speed of the load point e3 was 20 mm / min. The center position in the longitudinal direction of the pipe 20 was taken as the measurement point. The span S was set to 300 mm. The value (peak value) of the load F when the pipe 20 was broken was measured. The measured values are shown in Tables 5 to 7 above.

The raw materials used for preparing the matrix resin composition and the prepreg are as follows.
JER828EL: Mitsubishi Chemical's bisphenol A type epoxy resin (epoxy equivalent: 184-194)
JER4005P: bisphenol F type epoxy resin manufactured by Mitsubishi Chemical Corporation (epoxy equivalent: 1070)
JER154: Mitsubishi Chemical Corporation phenol novolac type epoxy resin (epoxy equivalent: 176-180)
-Polyvinyl formal: Vinylec E made by JNC
-Dicyandiamide: Mitsubishi Chemical Corporation DICY7
Urea derivative: DCMU-99 (3- (3,4-dichlorophenyl) -1,1-dimethylurea) manufactured by Hodogaya Chemical Co., Ltd.
・ Methyl ethyl ketone: Yoneyama Pharmaceutical Co., Ltd. ・ Carbon fiber: As described in Table 1

  From the results of Tables 5 to 7, it is shown that when the novolac-containing layer is disposed on the outside, the shaft strength is easily improved. The advantages of the present invention are clear.

  The shaft described above can be applied to any golf club.

2 ... Golf club 4 ... Head 6 ... Shaft 8 ... Grip s1-s11 ... Sheet (layer)
s23 ... united sheet s78 ... united sheet 20 ... pipe (shaft)
Tp ... Tip end of shaft Bt ... Butt end of shaft

Claims (7)

A laminate of fiber reinforced resin layers,
Has multiple full length layers,
The full length layer has a full length bias layer and a full length straight layer,
When the matrix resin includes a novolac-type epoxy resin layer as a novolac-containing layer, the full-length straight layer positioned outside the full-length bias layer includes the novolac-containing layer,
In the novolac-containing layer, the matrix resin contains an epoxy resin component,
The content Rn of the novolac type epoxy resin in the epoxy resin component is 3% by mass or more and 19% by mass or less,
When the average specific gravity of the novolak-containing layer constituting the full length straight layer is S1, and the average specific gravity of the inner layer of the full length bias layer and the full length bias layer is S2, the specific gravity S1 is higher than the specific gravity S2. Big golf club shaft. The full length straight layer has an outermost full length straight layer located on the outermost side among the full length layers,
The golf club shaft according to claim 1, wherein the outermost full length straight layer is the novolac-containing layer. Among the full length straight layers, the outermost N layer is the novolac-containing layer,
The golf club shaft according to claim 1, wherein N is 2 or more.   The golf club shaft according to claim 3, wherein the N is 3 or more. The full length straight layer which is the novolac-containing layer is provided with M layers,
The golf club shaft according to any one of claims 1 to 4, wherein all of the M layers are located on the outermost side of the full length layer. The fiber elastic modulus in the novolac-containing layer located outside the full length bias layer is 8 t / mm ² or more and less than 38 t / mm ² ;
The golf club shaft according to any one of claims 1 to 4, the fiber elastic modulus is 38 t / mm ² or more 70 t / mm ² or less in the full length bias layer. 7. The golf club shaft according to claim 6, wherein the fiber elastic modulus of all layers located inside the full length bias layer is 38 t / mm ² or more and 70 t / mm ² or less.

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